1. Field of the Invention
The present invention relates to an illumination optical system, an exposure device for manufacturing semiconductor devices such as IC's, LSI's and the like, imaging devices such as CCD's, and devices such as magnetic heads, and a method of manufacturing a device using the exposure device.
2. Description of the Related Art
In manufacturing a semiconductor device using photolithographic technology, a projection exposure device is conventionally used for exposing a transfer pattern of a photo mask (mask) to transfer the pattern to a substrate such as a wafer or a glass plate on which a photoresist is coated (hereinafter referred to as a "substrate"), through a projection optical system. In recent years, improvements in integration and definition in semiconductor devices have required the projection exposure device to have a higher resolution.
In order to comply with this need for higher resolution, a laser such as an excimer laser, which generates a pulsed beam, is used as a light source in the far ultraviolet region for the projection exposure device.
On the other hand, when a mask is illuminated with a beam emitted from a coherent light source, such as an excimer laser or the like, nonuniformity occurs in an illumination distribution due to interference fringes, thereby adversely affecting exposure precision. In order to avoid this problem, conventionally, the position of a beam incident on an optical integrator such as a fly's eye lens is shifted, or a mask is exposed using a plurality of pulsed beams while the phase of the interference fringes is changed so as to prevent nonuniformity in the illumination distribution due to the interference fringes from adversely affecting exposure precision.
However, in the above-mentioned methods, when the beam incident position of the optical integrator is shifted by a member, for example, a vibrating mirror, the member for shifting the beam incident position and means for driving the member are required. This complicates the configuration of the apparatus.